Earth Leakage Unit


An earth leakage unit detects current imbalance in trackside cabling. Early detection of cable degradation can prevent further cable damage and the potential hazards associated with this type of fault.

What does it do?

The Rowe Hankins earth leakage unit is a residual current circuit breaker, which is powered from the vehicle’s battery and measures the sum of the current in primary conductors passing through its aperture.

In DC earth leakage detection applications, the current in all supply conductors, both positive and negative, are measured.

During standard operation when there is no earth fault present in the system, the current in the “positive” and “negative” conductors cancel and the dectector alarm relay is energised.

The unit monitors for any current imbalance through the primary conductors, which indicates earth leakage. The current signal is filtered and rectified before it is fed into a comparator. If the current is greater than the detection level then a timer is triggered. If the current imbalance signal remains above the detection threshold for a set amount of time, the output relay is de-energised, resulting in a change in the relay contacts. The output relay remains locked in a de-energised state, regardless of the current input level. The system can only be reset by a power off and fault resolution event.

Features & benefits:

• For protection of DC power supply circuits.
• Locked fault output.
• Certified for rail applications.
• Bespoke settings for customer requirements.
• Compliant to standards:-

BSEN 50155: 2007, BSEN 60529: 1992, BSEN 50121-3-2: 2006, BSEN 61373: 2010